Typically, a new app for a new phone means new features (new + new x new = NEW). Or the same features, but better. The new version of Instagram for the iPhone 5 does not follow this track, as The Next Web first noticed: It actually removes the headline feature of Instagram 2.0, live filters, which showed you in real time what a particular filter would do to a photo you were about to take. While older iPhones retain live filters, the official plan is to phase them out entirely.

This is not exactly how most people expected Facebook to “ruin” Instagram. In fact, as Matt Panzarino points out, there’s shockingly little in the way of new Facebook bits — you can’t even log in with your Facebook profile.

Why would Instagram, a photo service, kill a major photo feature that it had invested significant engineering resources into developing, to the point that it rearchitected one of the core experiences in its app around it? Well, the thing is, Instagram doesn’t — and hasn’t — seen itself as a photo service, even if that’s how you (and everybody else) sees it. Founder Kevin Systrom told Mat Honan months ago: “I don’t like the idea of Instagram as a photo sharing service, and I don’t think it is. It’s very much a communication tool; it’s a visual communication tool.”

Instagram’s not about filters or even simply photos; it’s about something more in Systrom’s mind, to the point that he mentions Instagram and the printing press in the same breath in that interview. Instagram is “focused on how do we change the world in some real way,” according to Systrom, whose own use of filters in Instagram is sparing (just trawl through his feed). So I suspect John Gruber is correct when he reckons that removing live filters is part of a play to the “lowest common denominator” as “Instagram expands to more Android phones and other non-iOS platforms.” Killing a photo feature to get on more phones — every phone, basically — is a no-brainer.

And Instagram is already on a lot of phones. The mobile-only network passed 80 million users in July — picking up 30 million users in under three months — and it presumably has even more now. If it’s maintained the same trajectory of 10 million new users a month, it has 100 million users — or close to it — right now. AppData, a firm that specializes in app user numbers, estimated a couple weeks ago that Instagram had 11 million daily active users, and leaked numbers from comScore report claim that two-year-old Instagram has more daily active mobile users in the US than six-year-old Twitter does, 7.3 million to 6.9 million. (I believe Twitter has more daily active mobile users in the US than comScore estimates, though: Twitter had 140 million active users way back in March, and it presumably has millions more now; 60 percent of them log in from mobile; and it’s probably safe to assume that around half of its active users, or relatively close to half, still log in every day. Until the report’s public, we won’t know exactly how comScore arrived at the figure, though.)

Even if comScore’s numbers are off, it’s not impossible to imagine Instagram one day — soonish! — being more important to more people than Twitter. Twitter is a media company now, one that looks increasingly like Facebook in the way that it feels, breathes and moves. Instagram, or at least its founder, wants to be something more than that. It’s simply a question of whether Facebook’s acquisition is going to make that easier or harder. Systrom bet on the former. Either way, it’s clear that almost nothing will stand in the way of those ambitions — not even one of the things that made Instagram the thing that it is today.